Department: University of Delaware. Department of Geography.; University of Delaware. Department of Electrical and Computer Engineering.

Publisher: International Glaciological Society

Date Issued: 2015-10-01

Abstract: In this paper we explore simulated responses of electromagnetic (EM) signals relative to in
situ field surveys and quantify the effects that different values of conductivity in sea ice have on the EM
fields. We compute EM responses of ice types with a three-dimensional (3-D) finite-volume
discretization of Maxwell’s equations and present 2-D sliced visualizations of their associated EM
fields at discrete frequencies. Several interesting observations result: First, since the simulator computes
the fields everywhere, each gridcell acts as a receiver within the model volume, and captures the
complete, coupled interactions between air, snow, sea ice and sea water as a function of their
conductivity; second, visualizations demonstrate how 1-D approximations near deformed ice features
are violated. But the most important new finding is that changes in conductivity affect EM field response
by modifying the magnitude and spatial patterns (i.e. footprint size and shape) of current density and
magnetic fields. These effects are demonstrated through a visual feature we define as ‘null lines’. Null
line shape is affected by changes in conductivity near material boundaries as well as transmitter
location. Our results encourage the use of null lines as a planning tool for better ground-truth field
measurements near deformed ice types.